 Good morning and welcome back to the lecture series on bioelectricity. Today, we will start the module on the plant bioelectricity. So, as we have discussed in the, you remember in the first lecture, we talked about that we have divided the course into different modules, animal bioelectricity, plant bioelectricity, insect bioelectricity and few other some of the ancient molecules will be dealing with. So, following that pattern, so today we are initiating the plant bioelectricity. So, if you remember, we will be studying plant at three different level. So, even before I go about the plant, so whenever we talk about, so the way I have module this section is this, I will introduce you about the plants and where it really fits in the ecosystem and how the bioenergetics on the floor of earth is governed by plants and the overall anatomy of the plants. From there, we will move on to three different aspects of plants which involve transfer of charges or transfer of electrons and which eventually leads to two important things. One is the movement of the plants, the other one is the energy harvesting. So, coming back, after giving this brief background in tell you, so plants, if we look back in the ecosystem or in the whole food chain, our the whole life form depends on sun as the solar energy, that is very fundamental. So, these sun solar energy are being trapped by the green leaves by a very similar way by which a solar cell traps the solar energy and ejects an electron and generates power. Exactly by the same analogy, a plant traps the solar energy, ejects an electron and these electrons further helps in synthesizing very high energy rich molecules and these energy rich molecules are further utilized by the plant for synthesizing energy storage molecules and once the energy storage molecules are formed, the next level of life form the animals which cannot synthesize food directly from sunlight and from here and soil, they eat the plant and eventually once they die, the debris mix on the plant, mix in the soil and the food cycle goes on. So, just to give you a graphical representation of this, just to get an idea, let us get back. So, we are into this lecture into plant bioelectricity and as I have mentioned, we will divide this whole thing into different components. First of all, we will talk about the ecosystem, role of plants, energy harvesting and transfer. Then we will be talking about the classification of plants, classification of plants. After this, we will be talking about the mechanism of energy harvesting which essentially is called photo synthesis. Photo means light, synthesis means synthesizing energy rich molecules using light. So, then from there we will move on to the part of photosynthesis as such, but another section of it which will be plant movement and in this section, we will be talking about Mimosa protica or touch me not plant and venous light wrap. Apart from it, we will be picking up another small section within this which is dye sensitized solar cells. So, this is essentially an inspiration from flowers. So, this is the overall outline what we are going to dealt with which I was trying to tell you verbally that these are the aspects what we are going to deal with. So, coming back to the ecosystem part. So, essentially in the ecosystem what is happening is that, resume sun has the major source of energy. So, solar radiation reaching the flow of earth, the solar radiation is being picked up by the land plants and the water plants that is coming in the form of H nu. And within this machinery, there are all the light falls on these surfaces. There is an ejection of electron out here. This electron eventually leads to the synthesis of energy rich molecules. This energy rich molecule leads to the further synthesis of different storage molecules. And as I was telling you, these plants are eventually consumed by the animals. And again within animals, these animals are consumed by higher animals. And eventually all these dyes out, these all dyes out and increase the biomass of the soil and get transformed into organic matter. And these organic matter is eventually utilized by the plants again along with organic matter plus water plus minerals and in the presence of sunlight. The whole process goes on and on. And what we will be dealing essentially is in this zone where this whole energy transduction is taking place, which is essentially the process of photosynthesis. So, from here if I just refer back to previous slide what I was trying to tell you. So, this is the part, but just now I discussed with you the overall idea of the ecosystem. This is very essential to get a global picture that where we are really heading. And what is the inspiration of this whole process now coming back to this slide. So, this whole electron transfer what is happening in the on the surface of the leaves. So, essentially you can consider the vegetative cover on the floor of earth, whether it is in the water, whether it is in the land, they are very similar to the solar panels. So, essentially whole earth whatsoever percentage of earth discovered with vegetation is essentially functioning as a mechanism of nature by which solar energy is being trapped. And this specific molecules which has the ability to capture the sunlight and eject electron are inspiration for developing next generation of solar cells. So, what we essentially have to understand the structure of these molecules, the process which is governing the electron transport chain within nature and the process by which it synthesize the energy rich molecule. Once we understand this process we will draw inspiration from the current research where people are trying to emulate or mimic these kind of systems in order to develop next generation of energy harvesting devices, next generation of power sources. So, coming back to the classification where I was going. So, next what we will do, we will start with this part the classification of the plants. This is very essential before you could understand where this all these things fits in. So, coming back to the classification of the plants. So, plants could be broadly in a very simple manner plants could be classified into two groups. So, you could have plants which are growing in the land, you could have plants which are growing in the water. This is the broadest of all classification. Land plants, plants growing in water. And these land plants could be further classified into two categories, vascular plant, avascular plant. The vascular plants, avascular plant, this word means within the plants, the plants pick up water, plants pick up nutrients, plants synthesize different things. So, these happen through specific channels, it is just like within our body there are blood vessels which carries blood, there are limb vessels which are carrying limb. Exactly the same analogy holds true for plants where the plants have vessels which carries water and nutrients those are called xylem vessels. And they have vessels which carries energy synthesized energy rich molecules which also is called the plant sap. Those are carried through another series of vessel called flowing vessels. The xylem vessels I will draw it, they are separated from the flowing vessels by a series of dead tissues which ensure the xylem vessel is pretty much water proof of the whole tube through which the water moves through is kind of water proof on all the sides. So, the vascular plants are the one which has very specialized xylem and flowing vessels and avascular plants are the one which does not have the xylem and the flowing vessels. So, essentially avascular plants by default has to be a smaller shape, smaller size because they do not have any mechanism to distribute nutrients. So, they can only do by a diffusion process within a very small area or within a very small space as compared to a vascular plant which has specialized machinery to transport any kind of nutrients or water or nutrient to all parts of its system. So, not having that. So, vascular plant avascular plants. So, vascular plants are further classified into three groups. Those three groups are called angiosperm, gymnastperm and ferns. So, angiosperms are the ones which in which the seeds are covered with fleshy coating. So, these are the plants like mango or apple where you see the seed is deep inside and it is covered by a complete fleshy eatable matter. So, these falls on the angiosperm. Then you have the gymnastperms. These have naked seeds. There is no covering on the seeds and then you have the ferns. Ferns are though they have vascular system, but they are without and yet you have vascular plants. They do not have any specialized xylem or flowing vessel. So, these have, let me put it, xylem and vessels. So, a vascular plant, these includes moses and liver nodes and this what classifies us with the different plants which are found in the land. Whereas, on the other side, when we are talking about plants growing in water, they are mostly falling under the seeds. So, now all these plants have one common feature which is in the previous slide when I was speaking to you guys about this whole process of photosynthesis. So, they all have chlorophyll and they all synthesize food from the sunlight and this remain our central thematic for a long period of time in the world where we live. We always believe this, but certain extraordinary discoveries in the last century change the way we think. So, what I have drawn you is sun in the plants and synthesizing energy, animals are consuming it, all of them are dying, adding up organic matter. So, this whole process depends on sunlight, yet this whole mechanism is not the only way by which life has evolved. During 1970s, especially the this 1977, some of the teams of National Geographic and few other expert in oceanography, they were exploring in the sea pretty much deep down into the core or into the floor of this ocean and they found in there are several places or at least the first discovery was made in Galapagos Island deep inside where no sunlight ever reaches, where there are existence of high pressure, low temperature situation, there is something called hydrothermal vents. These are the fissures or these are the gap through which the from the inner core, the heat is kind of ejected out onto the floor of the ocean and that is why they found that complete dark exceptionally low temperature, they found life is thriving. What I will do in this context, I will send you some of the links for the videos which are available online, which will help you to appreciate and it was amazing to see how the life thrives in those hydrothermal vents. Hydrothermal vents and in and around hydrothermal vents, there are series of sulphide related molecules, iron dyes sulphide, iron copper sulphide likewise and several, there is no sunlight. So, let us again rewrite the previous graph. So, now we are talking about situation. So, if this is the ocean surface and if the sun is sitting here out here. So, most of the lifeform or the seaweeds what you see are growing either on the top of this and that is it, may be up to this maximum few feets underneath, but sunlight never reaches anything beyond it. That is it, maximum sunlight will reach this and where you will see the life. So, let me label it for you further understanding, this is the ocean surface, this green ones are there and now we are talking about a situation deep inside. So, we are out here, several feets underneath, this is where this is almost 600 to 700 or even more, this is the sea flow or the ocean flow and from here comes out all the hydrants, there is a formation of these hydrothermal vents out here. These are the black smokers, tin is white and black smokers. Now, I will give you this all those videos, link of the videos you will see, hydrothermal vents and white black smokers, these are also called the chimneys. And this is the zone which is kind of you know very lot of sulphides, iron, magnesium and series of them. This is a very hostile environment and here you see a series of light forms going through. So, then whether these light forms, now if you compare this situation, where there is no light reaching, how the electron transfer is taking place. So, there is no photosynthesis taking place in this situation, but if you compare this picture with this picture, where there is a sun which is directly hitting upon the leaves and if you see this picture now, there is no sun which is hitting upon the surface. So, these kind of light forms leads to 1977 changed our way we think, this leads to a new form of synthesis, new form of electron transport or electron transfer that falls under another like another form which is called chemo synthesis. And this part of chemo synthesis falls under all the ancient molecule will be dealing with especially with special reference to iron, disulfide and other molecules will be dealing with the whole chemo synthesis, where solar energy is not a essential criteria for electron transport. So, photosynthesis and chemo synthesis. So, now coming back to the classification of the plants where I was trying to classify it. So, the seaweeds now putting another one more site classification out here within the sea very deep inside you cannot call them plants there is another group of organism called Archaeans growing very low or no oxygen very high pressure fairly low temperature and first important the new sunlight deep inside the ocean floor these life forms thrive. So, these life forms essentially what will be dealing with the ancient molecules what I have discussed in the global scheme of science in the beginning that there are molecules which are not dependent in nature on solar energy or any form of light as such. So, coming back to the classification this is we told just to give you an overall picture that it is not always the sunlight which involves in the electron transport. So, talking about the inspiration what we are drawing. So, of course the way it will go is and there is one more thing. So, if I look at the now let us discuss the anatomy of the plant in very brief. So, I am not going to come back to this. So, I have given you the classification of the plant. So, you go back. So, this is what we are trying to do classification of the plant. So, ecosystem and here let me add one more thing after classification of the plant will be dealing with the very brief anatomy of plants. So, ecosystem of plant. So, we have talked about this part as of now we have talked about the overall classification of the plant. Now, we will be talking about the brief anatomy of the plant in this class. So, coming back to the anatomy of the plants. So, the plant has like if of course, here we are only talking about the mostly the classic angiospermic plant which has seeds and everything. So, if you look at a plant structure almost like this on that go down. So, underneath you have all the root system. Now, giving a normal picture here you have the flowers leads to the seeds and everything, here you have the leaves, here you have the main stem and here you have the root system. So, the way it works is sunlight is falling on these surfaces and water plus nutrients are traveling along this and all the assimilation taking place out here and the heritage molecules are stored along another series of assets. So, now what we will do? We will blow up the cross section of the stem of the root. So, if you see the cross section, cross section of a cross section, cross section will look something like this cross section has. So, this is not the right way let me just rub it off and do it again. So, you see there is a central canal which I have drawn in yellow. So, that is the one which is carrying what we are terming as the xylem vessels that is carrying the water up into the plants from the roots. So, this xylem vessel and the flowing vessels are all over up to the tip of the root all the way up to the tip of the shoot. They travel all along. So, there are pipes which are traveling along. So, it is something like let me show you by some simple chalk pieces which are lying here. They are like this. This is the vessel and surrounded by the flowing vessels. So, xylem vessel is in the center and surrounded by the flowing vessels. Imagine there are other chalks which are surrounding it and they are the flowing vessels. So, these central ones are the, this is your xylem which is allowing the water to move all the way up, water and nutrients. What you see in the flowing vessels on the other side and this side, these are the ones which are ensuring the plant sat or whatever the molecules. So, whatever the molecules which are being synthesized by the plant, the energy rich molecules or the storage molecules, they remain in the flowing and between the xylem and the flowing there is pretty much water proofing molecules which ensures none of the water is kind of lost. This gives the water proofing. What you see I am just putting the crosses on in between the xylem and the flowing vessels. So, this is kind of a water proofing of xylem vessels because this is very essential that the water is not being lost from the xylem vessel otherwise, you know there will be a absolute mix up and this water proofing is done by a series of molecules called lignins. Lignins are the ones which ensures that it is not being lost and if you see the cross section of this, if you just cut the cross section what you will see essentially is something like this. In the center and we see the xylem vessel and the peripheries you will see all the yellow just I will reverse the colors you do not get worried. So, this is the cross sectional view here you have the xylem and here you have the flowing vessels. There are multiple flowing vessels which are traveling all along and this will come very handy while we will be talking about the non-movement and coming back to the structure of the leaves which you have discussed as of now. There is something called pithiol which is here and these are the veins of the leaves which are carrying the nutrients and the water at the different parts of the solar harvesting mechanism. Apart from it what is important for you people to understand is why I have drawn the flower. So, this flower these flowers are the inspiration for the first slide if you go back I mentioned about the disensitized solar cell. All these different dyes present on the flower they all have ability to trap sunlight and eject electron only difference between these and the major molecule in photosynthesis which is called chlorophyll is that the other dyes have lower molar absorption coefficient will come to all these things molar absorption and that is why they do not directly take part in photosynthesis. Instead they try to concentrate the solar energy on the leaves and help the chlorophyll molecule to move ahead and perform the function of trapping the sunlight and eject the electron. But those molecules are the inspiration for last almost three decades since 1980's it has all started with the discovery or with the finding by Gretzel. So, we will be talking about the Gretzel cells out here which are direct inspiration from nature from the structures of the flowers all the dyes of the flowers which are derived from here are used for. And of course, there are several dyes which are synthesized after getting inspiration from the floral dyes. So, overall in this module we will be talking in this module we will be talking about. So, after giving you this brief outline of the anatomy classification. So, back to my second slide where I was now I have talked about the anatomy. So, the ecosystem I have done I will give you a brief idea we have talked about the classification of the plants we have talked about the brief anatomy of the plant. And of course, I told you why from where the inspiration for dye sensitize solar cells. So, now what we will do after this. So, with this brief introduction about the plant systems and how they are transferring electrons and everything. I will move on to the real process where the plants are harvesting the sunlight and ejecting electrons and that will fall under photosynthesis. So, I will not come back to all these things any further. So, now on I will be talking about in the next class what we will be starting is I will be talking about the overall photosynthetic machinery, the chlorophyll molecule, the different types and their spectral properties. Then we will be talking about the electron transport chain and likewise. So, I will close in here and in the next class we will continue with this, but then we will be directly talking about the energy harvesting through photosynthesis, photosystem 1, photosystem 2. Then C3, C4 plants and the inspiration drawn out of these photosynthesis in terms of water splitting complex and chlorophyll for developing next generation of energy harvesting devices. And from there we will move on to the plant movements where even could be considered the rudimentary nervous system of the plant and the tailpiece of this section will move on to the disincentive solar cells. Thanks a lot.